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Fasting for Better Brain Performance with Dave Asprey

Dave Asprey is the Founder & Chairman, Bulletproof. He is a three-time New York Times bestselling science author, host of the Webby award-winning podcast Bulletproof Radio, and has been featured on the Today Show, CNN, The New York Times, Dr. Oz, and more.

Over the last two decades Dave, the “Father of Biohacking”, has worked with world-renowned doctors, researchers, scientists, and global mavericks to uncover the latest, most innovative methods, techniques, and products for enhancing mental and physical performance. The creator of the Bulletproof Diet and innovator of Bulletproof Coffee, Collagen Protein supplements and many more advances in commercial wellness products, Dave’s mission is to empower the entire globe with information and knowledge that unlocks the Super Human in everyone at any age. The proof of these advancements includes better sleep, energy, and expanded capacity for all.


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How do you fast for better brain performance? 

Today, I’m excited to welcome back our very first guest, Dave Asprey, to the show to talk about fasting for your brain. Dave is a Silicon Valley tech entrepreneur who’s also known as “The Father of Biohacking.” He is a three-time New York Times bestselling science author and host of the Webby award-winning podcast, Bulletproof Radio. 

Here to discuss his new book, Fast this Way, Dave expounds on his journey to losing 100 pounds and turning his brain back on. He shares the dangers of over-fasting, the powerful impact that fasting can have on your personal development, and more! 

According to Dave, much of the challenge of fasting is mental and not just about willpower; it’s about belief systems. He teaches his audience how to feel safe getting on the fasting journey. 

If you’ve ever considered fasting or wondered how to do it “the right way,” this episode is for you.

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  • We know that fasting is good for your brain, it makes you feel younger and helps you lose weight, yet most people aren’t fasting or are making mistakes when fasting.
  • Dave wanted to write a book that other people could relate to, so he shares his own experience with losing 100lbs and turning his brain back on.  The two things that triggered Dave’s journey were the realization that he was afraid of being alone and afraid of being hungry.
  • In the book, he also shares the right way to fast and the science behind it — including what supplements to take and what foods to eat.
  • Fasting means going without, so it is not limited to food. Going without alcohol is a type of fast. You can go without water, which is called a dry fast.
  • Much of the challenge of fasting is mental and not just about willpower; it’s about belief systems.
  • People need to know how to feel safe when going on a fasting journey and that’s what Dave teaches his audience.
  • He teaches how to address the voice in your head that limits you and may cause you to scare away from the idea of fasting.
  • Even experienced fasters have challenges with fasting.
  • Those that have experienced the value and practice fasting regularly can sometimes over-fast without recognizing unhealthy signs.
  • Just like you can over-exercise, you can over-fast.
  • Someone who has convinced themselves of the benefits of fasting may attribute poor sleep to the need to fast more. The reality is that the body is indicating signs that something is not right.
  • Some negative effects of over-fasting include poor sleep, hair loss, and changes in the menstrual cycle (for women). **Men and women are affected differently**
  • The goal of Fast This Way is to teach people how to get started with fasting without pain and other negative side effects, how to avoid over-fasting, and how to fast for spiritual growth.


  • Fasting for spiritual growth is different from fasting for your metabolism. It’s not just about food.
  • The hardest fast of all is in the last chapter of his book when he challenges people to fast from ‘hate’ for example. The idea is to do an “intermittent hate fast” where you challenge yourself to go without thinking one bad thought about anyone or anything for 4 hours.
  • Fasting is such a powerful tool because it can give you energy and clarity to show up for each day to do whatever you want to do.
  • You can then use that new energy to train your brain to be better and do the deep, personal work of becoming a better version of yourself.
  • If you are tired all the time, your desire to learn decreases or is challenged because of a lack of energy.
  • Fasting creates freedom.
  • When you buy the book, Dave will teach you how to fast for free, ending with a one or two day spiritual fast that helps to address the voices in your head through meditation and deep thought work.
  • Fasting can give you more energy and teach you how to have less negative and wasteful thoughts.
  • There is a study in his book that shows that 15% or more of the average person’s thoughts are about what their next meal will be. If he can teach you how to turn off hunger and stop thinking about food during a fast, you could get 15% more thoughts every day to do whatever you want from them.


  • You can have more with less. It’s not always about cutting calories.
  • Timing is a significant factor when it comes to fasting.

What seems to work best for people is having an early dinner:

  • Eat dinner at 5:30/6 PM. (6 PM – 10 PM, 4 hours)
  • Go to sleep at 10 PM. (10 PM – 6 AM, 8 hours)
  • Skip breakfast & have an early lunch at 10 AM. (6 AM – 10 AM, 4 hours)
  • That’s 16 hours of fasting.

Fasting is all about knowing what to fast for the right amount of time.


Every spiritual practice includes some form of fasting to put you in a special state.

After going multiple days without food, you gain energy and clarity of thought for two reasons:

  • 1. Things you eat every day make your brain weak. You don’t necessarily know what those things are, but tons of plants have toxins in them. When you are fasting, you don’t get any toxins from your food.
  • 2. After about 3 days, your body goes into ketosis where your body begins to burn fat stores. Fat contains more electrons than sugar, giving off more energy for your brain.

If you do ketosis too often or you over-fast and never eat carbs, it can be bad for your brain because your brain wants more sugar than it wants ketones.

  • Over time, keto makes the brain weak because you stop maintaining the brain. You should go into and out of ketosis. When you are out of ketosis, you can take MCT oil that gives you ketones for your brain.
  • More energy in and fewer toxins in equals more freedom.
  • Think about fasting as learning how to feel safe while going without. You can fast from junk food, carbs, animals, alcohol, and even hate. You just have to learn how to go without something you feel like you need.
  • You will die from a lack of sleep way before you will die from a lack of food.
  • You feel like you will die if you don’t eat tomorrow, but you have the capacity to go three months without food. The body is not telling you the truth in these situations.
  • Fasting is the idea of getting closer to reality and understanding that what you think you need you don’t need, you just want. Learning that creates peace inside of you.
  • We are wired in our cells to support other humans, but it’s harder to do if you are afraid all the time, hungry all the time, and there is no love in your life.
  • Fasting the right way will increase clarity in your mind, increase physical energy, and creates a huge amount of mental space to improve the way your brain works.


  • Take a screenshot of this episode, tag us on social media (@Dave.Asprey & @JimKwik), and share your greatest “aha!” moment from this episode with us.
  • For more from Dave, check out his website.
  • Get Dave’s book, here, and join the Fasting Challenge.

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